Grate



(No Model.)

AH. R. LUTHER.

GRATIS.

No, 529,504. Patented Nov. 20, 1894,

n Le;

l Unita-tao raras Parent* @prima HENRY R. LUTHER, OF CAMBRIDGE, MASSACHUSETTS.

GRTE.

SPECIFICATION forming part of Letters Patent No. 529,504, dated November 20, 1894 Application filed March 15,1894. Serial No. 503.809. (No model.)

To all whom it may concern:

Be it known that I, HENRY R. LUTHER, of Cambridge,countyof Middlesex, State of Massachusetts, have invented an Improvement in Grates, of which the following description, in connection with the accompanying drawings, is a specification, like letters on the drawings representing like parts.

United States Patent No. 485,684, dated November 8, 1892, illustrates a type of fuel support or grate, consisting of alternately arranged high and low grate surfaces, the latter arranged in long pockets in the former, the side walls of said pockets being imperforate. When grates of this type or construction are placed in practical use it has been found that the intensity of the re upon the upper grate surfaces along the edges of the pockets is such as to melt down the metal of said walls and in a comparatively short space of time seriously injure the grate. Again, when grates of ordinary construction are replaced by pocket grates of the type above referred to the fuel upon the pocket grates develops a heat much more intense than the same quantity of fuel upon the old form of grate. In many instances, however, when the change from the old form of grate to the pocket grate is made, such change is for the purpose of obtaining the same quantity of heat as before but with a less consumption of fuel, making it necessary to carry a more moderate tire upon the pocket grate to obtain the required heat than was formerly required upon the old form of grate. In practice, however, I have found it very difficult to so control the fire upon the pocket grate as to produce a'moderate heat, this diiiiculty being caused by the lack of sufficient means for properly controlling or regulating the quantity of air permitted to rise between the pockets and through the upper grate surfaces upon which the areas of most intense tire of incandescence is carried.

The object of this invention is, first, to provide means for narrowing the section of incandescence or intensely heated sections of tire upon the upper grate surfaces to thereby free the side walls of the pockets to a greater or less extent from the damaging effects of intense heat, and second, to provide means for restricting the amount of air admitted to the upper grate surfaces to support the combustion thereupon without restricting the area of said upper grate surfaces.

In the construction herein shown and embodying my invention I am enabled to attain both of these objects.

In accordance with my invention I provide the exterior walls of the pockets with what I term bafiie surfaces integral with or independent of the said side walls but inclined inwardly toward each other to reduce the area of opening through which the air must pass in rising to the upper grate surfaces between the side walls.

In the drawings, Figure l represents in top or plan View a large pocket grate embodying my invention; Fig. 2, a cross section of the same on the dotted line x.'r, and Fig. 3, a longitudinal section on the dotted line y-y.

Referring to the drawings, the grate shown consists of alternately arranged high grate surfaces a and low grate surfaces b, the latter being arranged in pockets p, Fig. 2, herein shown ,as extending the entire length of the grate and provided with imperforate side walls p', but which so far as this invention is concerned need not be of such great length. In the present instance the lower grate surfaces b are suspended on pivots b', said lower grate surfaces being divided into several sections in order that they may be rocked about said pivots; suitable means being provided by which to rock said lower grate surfaces, but which do not constitute a part of this invention and need not be herein further described. The upper grate surface, as usual in all grates, is provided with air openings d through which air may rise to support cornbustion of fuel upon the grate.

In pocket grates as heretoforecoustructed, the outer side walls of the pockets have been perfectly straight, permitting air to riseacross the entire widths of the upper grate surfaces and through the openings d in said upper surfaces to maintain intensely hot fires upon the several upper grate surfaces, the cross area of said intensely hot sections being roughly indicated by the dotted line 2 cornposed of alternate dashes and dots, Fig. 2. It will be seen that, when the air is thus admitted across the entire width of the upper grate surfaces, the sections of intensely hot IOO fire overlap the side walls of the adjacent pocketsv with the resultV that said walls are in many cases rapidly melted down.

In accordance with this my present invention I restrict the admission of air to the upper grate surfaces between the pockets, preferably by the use of what I term baffle survfaces c, shown as formed integral with the side walls of the pockets, but which so far as this invention is concerned may be independent of said walls and suitably attached thereto. These bafle surfaces are inclined inwardly and upwardly toward each other, as shown in Fig. 2, and are separated to leave a restricted or narrow opening c beneath the longitudinal center line of an upper grate surface, and through this restricted opening all the air which passes through the grate surfaces above it must pass. The result of this is that the supply of air to the upper'grat-esurfaces is more nearly restricted to thecenter of said surfaces to thereby reduce the cross-sectional area of the intensely heated portions of the re, to an area roughly designatedy by dotted line-3. Itwill be seen that by narrowing up the cross-sectional area of the intensely heatedy section of. fire upon the upper grate surfacesthe side Walls of thepocketsare subjected to less heat and are thereforeenabled to stand for a much longerperiodof time.

The other object attained by my invention and which in many cases is quite as important as the saving of the pocket walls, is that, by reducing the areas of intensely heated-sections, the aggregate heat produced by the fuel upon the grate isless than when a full supply the intensely heated sections are much larger. This is equivalent to carrying a more inoderate re and enables the pocket grates of thesame area as grates of the former type to replace the lattervgrates and to produce the same heat as-the old type of grate, but with less expenditure of fuel.

By varying the opening c t-o admit more or less air, and by'changing the inclination and vertical location of thebaftle surfaces,

the cross sectional area of intensely heated. sections upon the upper grate surfaces, and the resultant heatv produced, may be varied, yet protecting, to agreateror less extent, the side walls of the pockets.

A further and added advantage resulting from the use of my invention is that the air rising to the upper grate surfaces is compelled to pass through a restricted opening c and is thereby raised to a higher tempera- I ture by the heated bale surfaces and theside Walls of the pockets, than where the opening is muchlarger, the air thus mingling with the fuel upon the upper grate; surfaces in a much higher temperature, and in readiness to minglel more thoroughly and perfectly with the gases escaping with the fuel, than with the old form of pocket grate. It will be noticed that I have provided the space between the side`pockets andthe vertical side plate a2 of the grate, with baffle surfaces at one of their sides only, viz: the sides adjacent the pockets in order to crowd the air toward the said side plates 0L2 and maintain a more intense heat along the extreme edges of the grate than has heretofore been possible. This not onlyvproduces a more uniform re, but also brings the most intense heat along the edge of the grate next the Water space surrounding thel fire, to thereby raise the water within said space to a highertemperature and increase the efficiency of the boiler.

Fig. 3, shows thebaftle surfaces as extending the entire length of the grate along the sidewalls of the pockets. It will be noticed that Whilev I restrict the quantity of airk admitted to the upper grate surfaces, yet. the area ofsaid upper grate surfaces is not reduced, I thereby obtaining a combination and resultnot heretofore known so far as I am aware.

Thisinvention is not restricted to the particular form of pocket grate herein shown, as it is applicable to any'shape, size or arrangement of pockets, that depending entirely upon the character of work for which the grate is designed. Neitheris the invention restricted tothe particular sh ape or `construction of baffle surfaces herein shown, nor to the location oradjustment of the same shown, all of which may bevaried to meetf different requirements of surfaces. of air is admitted to said upper grates and I claim- I. In a grate-of the typedesc'ribed, the combination with the upper and lower grate surfaces, the latter arranged in pockets in the former, of abaffle surface projecting from the outside of the'pocket wall to restrictthe area of opening through which air may pass tothe upper grate surfacel above it without restrictingthearea of such upper grate sur- ;faces, substantially as described.

2f. Inv a gratie ofthe class described, the combination with upper and lower grate suriaces,the latter arranged in pocke'tsin the former, of bafiie surfaces arranged beneath the said upper grate surface and projecting inwardly toward each other fromthe adjacent sidewalls of the pockets to thereby/restrict thel opening through which air may pass to the upper grate surface abovesub stantially as and for the purpose specified.

In testimony whereof I have signed. my name tothis specification in the presence of two subscribing witnesses.

HENRY R. LUTHER. Witnesses:

FREDERICK L. EMERY', AUGUSTA E. DEAN.

IOO 

